The present invention relates to a pattern shape of a connecting terminal stored as a library. The pattern shape is suitable for use in pattern layout with an automatic conductive pattern layout machine (Computer-aided design: CAD), one of semiconductor IC design processes.
A semiconductor IC is manufactured, based upon a pattern layout design, in which information regarding the combination and disposition of logic circuits is included. The pattern layout design is conducted utilizing the automatic conductive pattern layout machine that is operated by an automatic conductive pattern layout program. The automatic conductive pattern layout machine stores a library that is an aggregation of structures of a pad, an I/O cell, an inverter, a NOR circuit and so on formed with a predetermined design rule. A desired structure is read out from the library onto the screen of the automatic conductive pattern layout machine to determine a suitable layout of the structures and conductive patterns connecting the structures.
Each structure is formed according to standard requirements of a minimum space between the conductive patterns and a minimum conductive pattern width determined by the predetermined design rule. Each structure has a connecting terminal having the minimum conductive pattern width. The structures are read out from the library onto the screen having grids aligned at intervals according to the minimum space between the conductive patterns of the automatic conductive pattern layout machine. The structures are located at positions corresponding to the grids. Therefore, a library of structures formed according to a one micron design rule, for example, can be used on the screen to make a new pattern layout according to the one micron design rule without any problems, because the same minimum spaces is provided between the conductive patterns.
However, where the structure designed with according to the one rule is read out to the screen having grids at intervals of 0.8 micron, for example, for the design of an IC device of higher integration, the structure does not match to the grids. Therefore, the conductive pattern may not be located at the position of the connecting terminal of the structure. In such a case, the conductive pattern cannot connect the structures because of the narrower minimum conductive pattern width. A library under the prior art is not flexible and not efficient, requiring a new library for a new design rule.
It is an object of this invention to provide a library with broader flexibility, enabling the library formed according to a (preset) design rule to be used on a finer design rule.
In order to accomplish the foregoing object, the present invention adopts the following new structure. A library according to the present invention includes structures designed with a predetermined design rule. The library has a main part including one or more circuit elements, and a connecting terminal connected to the main part. The connecting terminal has a width less than a minimum space between the conductive patterns of the predetermined design rule. The library further includes a head portion connected to the connecting terminal at the end thereof. A width of the head portion is greater than the minimum space between the conductive patterns of the predetermined design rule.